Bill Fellows has a script to standardize default constraint names:
This week I’m dealing with synchronizing tables between environments and it seems that regardless of what tool I’m using for schema compare, it still gets hung up on the differences in default names for constraints. Rather than fight that battle, I figured it’d greatly simplify my life to systematically rename all my constraints to non default names. The naming convention I went with is DF__schema name_table name_column name. I know that my schemas/tables/columns don’t have spaces or “weird” characters in them so this works for me. Use this as your own risk and if you are using pre-2012 the CONCAT call will need to be adjusted to classic string concatenation, a.k.a.
Click through for the script and be sure to check out Robert’s comment. You can also revise this script to “rename” (i.e., drop and re-create) foreign key or check constraints, though those might take a while depending upon how much data you’ve got.